/*
 * Copyright (c) 2018 Zilliqa
 * This source code is being disclosed to you solely for the purpose of your
 * participation in testing Zilliqa. You may view, compile and run the code for
 * that purpose and pursuant to the protocols and algorithms that are programmed
 * into, and intended by, the code. You may not do anything else with the code
 * without express permission from Zilliqa Research Pte. Ltd., including
 * modifying or publishing the code (or any part of it), and developing or
 * forming another public or private blockchain network. This source code is
 * provided 'as is' and no warranties are given as to title or non-infringement,
 * merchantability or fitness for purpose and, to the extent permitted by law,
 * all liability for your use of the code is disclaimed. Some programs in this
 * code are governed by the GNU General Public License v3.0 (available at
 * https://www.gnu.org/licenses/gpl-3.0.en.html) ('GPLv3'). The programs that
 * are governed by GPLv3.0 are those programs that are located in the folders
 * src/depends and tests/depends and which include a reference to GPLv3 in their
 * program files.
 */

#ifndef __JOINABLEFUNCTION_H__
#define __JOINABLEFUNCTION_H__

#include <chrono>
#include <functional>
#include <future>
#include <vector>

/// Utility class for executing a function in separate join-able threads.
class JoinableFunction {
  std::vector<std::future<void>> futures;
  bool joined;

 public:
  /// Template constructor.
  template <class callable, class... arguments>
  JoinableFunction(int num_threads, callable&& f, arguments&&... args) {
    std::function<typename std::result_of<callable(arguments...)>::type()> task(
        std::bind(std::forward<callable>(f), std::forward<arguments>(args)...));

    for (int i = 0; i < num_threads; i++) {
      futures.push_back(std::async(std::launch::async, task));
    }

    joined = false;
  }

  /// Destructor. Calls join if it has not been called manually.
  ~JoinableFunction() {
    if (!joined) {
      join();
    }
  }

  /// Joins all the launched threads.
  void join() {
    for (auto& e : futures) {
      e.get();
    }

    joined = true;
  }
};

#endif  // __JOINABLEFUNCTION_H__